Structural and synthetic studies on insect molting hormones, i.e., ecdysones, and their catabolic congenors will be undertaken based on organic chemical techniques and ideas. These will constitute mainly the following two methods: 1) extensive use of high-speed liquid-chromatography for the purification of the active principle, and 2) carbon-13 nmr, both chemical shifts and spin-lattice relaxation times (T1) for structural analysis. The ultimate goal of the proposed project is: 1) to rigorously establish the biosynthetic and metabolic pathways of ecdysones and related compounds, and 2) to attempt to draw conclusions on the role of biological conversions of the "ecdysone-like" steroids with respect to their place in the overall scheme of ecdysone action. More specifically, chemical conversions of ecdysones to prepare rare and physiologically important ecdysones and to elucidate the stereostructures at the chiral centers in some of the ecdysone side-chains are proposed. Microbial transformations of ecdysones and related steroids to obtain useful ecdysones will be attempted. We also propose to synthesize aza-ecdysones possessing nitrogen in the ecdysone side-chain as possible molting inhibitors. We hope that unambiguous establishment of biosynthetic and metabolic pathways of ecdysones in insects through spectroscopic and synthetic studies, with specifically labeled steroids, will contribute to the understanding of ecdysone action on a molecular level.